1. Field of the Invention
This invention relates to the use of dimethyldiallylammonium chloride homopolymers as the active antimicrobial agent in disinfecting and/or preserving solutions for contact lenses.
2. Description of the Prior Art
This invention relates to disinfecting and preserving contact lenses, particularly soft contact lenses. When the term "soft contact lenses" is used herein, it is generally referring to those contact lenses which readily flex under small amounts of force and return to their original shape when released from that force. Typically, soft contact lenses are formulated from poly(hydroxyethyl methacrylate) which has been, in the preferred formulations, crosslinked with ethylene glycol dimethacrylate. For convenience, this polymer is generally known as PHEMA. Soft contact lenses are also made from silicone polymers typically crosslinked with dimethyl polysiloxane. As is known in the art, conventional hard lenses, which cover only the cornea of the eye, usually consist of poly (methylmethacrylate) crosslinked with ethylene glycol dimethacrylate.
Hard contact lenses do not absorb appreciable amounts of water as do some soft contact lenses and thus the use of harsher disinfecting and cleaning bacterial activity or synergistic effect. The fatty quaternary polymers and copolymers are stated to be useful in treating circulating water systems and swimming pools and other bodies of stagnant water to inhibit algae and bacteria.
U.K. patent application No. 2,027,040A discloses the use of water soluble terpolymers of diallylamine quaternary salts as sterilizing agents for contact lenses. The application teaches that each of the three types of monomers must be present in order to obtain an effective eye care solution. The N-substituents for each class of monomers are respectively (a) low-low, e.g., dimethyl, (B) low-medium, e.g., methyloctyl and (C) low-higher, e.g., methyllauryl or methylcetyl, in molecular size; B:C being usually 5:1 to 0.333:1 (preferably 2:1 to 1:1) in weight ratio, and species less than 10,000 or preferably 20,000 m.w. usually being removed, have surprisingly effective sterilizing activity, e.g., against Candida while (a) not accumulating in soft contact lenses, whereby they can be used as an overnight, non-irritant, aqueous, sterilant solution at concentrations below 0.1 weight percent, e.g., 0.05 or less and (b) not penetrating skin or like membranes whereby aqueous formulations can be used as topical disinfectants without systemic side effects.